ARM: dts: qcom: Add SDX55 platform and MTP board support

Add basic devicetree support for SDX55 platform and MTP board from
Qualcomm. The SDX55 platform features an ARM Cortex A7 CPU which forms
the Application Processor Sub System (APSS) along with standard Qualcomm
peripherals like GCC, TLMM, BLSP, QPIC, and BAM etc... Also, there
exists the networking parts such as IPA, MHI, PCIE-EP, EMAC, and Modem
etc..

Currently, this basic devicetree support includes GCC, RPMh clock, INTC
and Debug UART.

Co-developed-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20201126083138.47047-3-manivannan.sadhasivam@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>